AM29LV128MH93REF datasheet(29/66 Pages) AMD

29 / 66 page

January 31, 2007 25270C7

Am29LV128MH/L

D A TA

SH EET

COMMAND DEFINITIONS

Writing specific address and data commands or se-

quences into the command register initiates device op-

erations. Table 10 and Table 11 defines the valid

dress and data values or writing them in the improper

sequence may place the device in an unknown state.

A reset command is then required to return the device

to reading array data.

All addresses are latched on the falling edge of WE#

or CE#, whichever happens later. All data is latched on

the rising edge of WE# or CE#, whichever happens

first. See “AC Characteristics” on page 47 for timing di-

agrams.

Reading Array Data

The device is “automatically set to reading array data

after device power-up. No commands are required to

retrieve data. The device is ready to read array data

after completing an Embedded Program or Embedded

Erase algorithm.

After the device accepts an Erase Suspend command,

the device enters the erase-suspend-read mode, after

which the system can read data from an y

non-erase-suspended sector. After completing a pro-

gramming operation in the Erase Suspend mode, the

system may once again read array data with the same

exception. See “Erase Suspend/Erase Resume Com-

mands” on page 35 for more information.

The system must issue the reset command to return

the device to the read (or erase-suspend-read) mode if

DQ5 goes high during an active program or erase op-

eration, or if the device is in the autoselect mode. See

the next section, “Reset Command,” for more informa-

tion.

See “Reading Array Data” on page 29 in the Device

Bus Operations section for more information. “See the

table, “Read-Only Operations” on page 47 for the read

parameters, and Figure 14 shows the timing diagram.

Reset Command

Writing the reset command resets the device to the

read or erase-suspend-read mode. Address bits are

don’t cares for this command.

The reset command may be written between the se-

quence cycles in an erase command sequence before

erasing begins. This resets the device to the read

mode. Once erasure begins, however, the device ig-

nores reset commands until the operation is complete.

The reset command may be written between the

sequence cycles in a program command sequence

before programming begins. This resets the device to

the read mode. If the program command sequence is

written while the device is in the Erase Suspend mode,

writing the reset command returns the device to the

erase-suspend-read mode. Once programming be-

gins, however, the device ignores reset commands

until the operation is complete.

The reset command may be written between the se-

quence cycles in an autoselect command sequence.

Once in the autoselect mode, the reset command

must be written to return to the read mode. If the de-

vice entered the autoselect mode while in the Erase

Suspend mode, writing the reset command returns the

device to the erase-suspend-read mode.

If DQ5 goes high during a program or erase operation,

writing the reset command returns the device to the

read mode (or erase-suspend-read mode if the device

was in Erase Suspend).

Note that if DQ1 goes high during a Write Buffer Pro-

gramming operation, the system must write the

Write-to-Buffer-Abort Reset command sequence to

reset the device for the next operation.

Autoselect Command Sequence

The autoselect command sequence allows the host

system to access the manufacturer and device codes,

and determine whether or not a sector is protected.

Table 10 and Table 11 show the address and data re-

quirements. This method is an alternative to that

shown in Table 3, which is intended for PROM pro-

grammers and requires V

ID on address pin A9. The

autoselect command sequence may be written to an

ad dr ess

t h a t

eith er

th e

r e a d

o r

erase-suspend-read mode. The autoselect command

may not be written while the device is actively pro-

gramming or erasing.

The autoselect command sequence is initiated by first

writing two unlock cycles. This is followed by a third

write cycle that contains the autoselect command. The

device then enters the autoselect mode. The system

may read at any address any number of times without

initiating another autoselect command sequence:

A read cycle at address XX00h returns the manu-

facturer code.

Three read cycles at addresses 01h, 0Eh, and 0Fh

return the device code.

A read cycle to an address containing a sector ad-

dress (SA), and the address 02h on A7–A0 in word

mode returns 01h if the sector is protected, or 00h if

it is unprotected.

The system must write the reset command to return to

the read mode (or erase-suspend-read mode if the de-

vice was previously in Erase Suspend).

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